Question

Maximum Amplitude of an amplitude modulated 10V and minimum amplitude is 5V. Find its modulation index?

(a) 0.65

(b) 0.9

(c) 0.33

(d) 1

This question was posed to me during a job interview.

My question is taken from Power Calculation topic in division Amplitude Modulation of Analog Communications

Answer 1

Correct choice is (c) 0.33

Explanation: We know, Modulation Index(µ) = (Vmax-Vmin)/(Vmax+Vmin),

   Where, Vmax = Maximum Amplitude of an amplitude modulated = 10V

                Vmin = Minimum amplitude  of an amplitude modulated = 5V

Therefore, µ = (10-5)/(10+5) = 0.33.